Los días 7 y 8 de mayo organizamos en la Fundación Ramón Areces con la Fundación General CSIC el Simposio Internacional 'Microbiología: transmisión'. La "transmisión" en microbiología hace referencia al proceso por el que material genético es transferido de una célula a otra, de una población a otra. Es un proceso clave para entender el origen y la evolución de los seres vivos. El objetivo de esta reunión era conocer mejor la logística de la transmisión para ser capaces de modular o suprimir algunos procesos de transmisión dañinos.

1. Transmission,
Introgression,
and Evolution
Fernando Baquero
Department of Microbiology, Ramón y Cajal University Hospital,
Division of Biology and Evolution of Microorganisms, IRYCIS, Madrid,
Spain
International Symposium Series: Microbiology
TRANSMISSION

2. Machinery, transmission of force between machines or
mechanisms
Transmission

4. Transmission
Nuclear fission: transmission of energy

5. Globalized travel and trade networks Hufnagel et al., 2004
Transmission

6. Transmission

7. Transmission
(memes)

8. Transmission

10. Transmission

11. Transmission

13. Infective
phage
Infective
plasmid
Infective
gamete
Infective
bacteria (cell-
to-cell)
Infective
bacterial
community
(invading
ecosystems)
Infective
bacterial
population (into
a microbiome)
Transmission

14. Transmission
In Latin, transmission = transmittere, more in the
sense of sending across, cause to go across, transfer,
pass on, from trans- "across" + mittere "to send”.
In Greek, transmission = μετάδοση (metádosi), with
the sense of “sharing” or “exchange” by “interaction”,
something flowing from one entity to another one.

15. Introgression
• Introgression derives from Latin: introgredior , “to step in, enter,
penetrate”
• Introgressive descent, the genetic (biological) material of a particular
evolutionary unit propagates into different host structures and is
replicated within these host structures*
*Slightly modified from: Bapteste, López, Bouchard, Baquero, McInerney, Burian, PNAS 109:18266, 2012)
......
...
........
..
b d

16. Recombination
Introgression of complex biological objects
As bacterial communities in microbiota

17. Hypotheses on the vertical transmission mechanism of the obligate aphid symbiont Buchnera
from a maternal bacteriocyte to an early embryo
Koga R. et al., PNAS 2012

18. Modified from: Dominguez-Bello et al., PNAS 2010; Reid G, Busscher HJ et al. Nature Reviews Microbiology, 2011.
Lactobacillus,
Prevotella, Sneathia
acquired by vaginal
delivery
Vertical Microbiota Transmission and
Introgression (mother-child)

19. Evolution
From Latin, evolutionem "unrolling (of a book)“.
Modern use in biology first attested 1832 by the
IntrogressionTransmission

20. Captured retroviral envelope
syncytin gene and the origin of
mammals. Heidmann T, et al. PNAS
110:E828-37 (2013) ; Cornelis et
al.,
Introgression and Evolution
• Intestinal microbiome and the evolution
of herbivors
• Viruses and the origin of mammals
• Endosymbiotic bacteria and
insects evolution
• Mitochondrial introgression and
eukaryotic cells
Watson RA: The impact of sex, symbiosis and modularity on the gradualist
framework of evolution. Cambridge (Massachusetts): The MIT Press; 2006
Clonalization and Speciation

21. Introgression of metabolic bacterial genes: a recurrent
evolutionary theme at the origin of novel composite lineages
Méheust, López and
Bapteste. Trends Ecol Evol.
2015 Mar; 30(3): 127–129.
Metabolic bacterial genes
and the construction of
high-level composite
lineages of life
Metabolic bacterial genes
contributed to all major
evolutionary transitions.

22. Transmission

23. Transmission

24. • Charles Sanders Peirce (1839–1914), father of Semiotics.
"A sign, is something which stands to somebody for something in
some respect or capacity“. In: “Speculative Grammar”, from Duns
Scotus Grammatica Speculativa.
• Every biological entity (from genes to microbial communities)
is also a sign and a signal
Microbes as Signs and Signals
Sign = Information
Signal = Instruction
Informative
surfaces
Signals-as-objects (Kopec, G., 1980)
Of course, no “intentionality”
to inform or instruct, but
“programs designed by
humans to produce a result
are similar to, and may be
indistinguishable
from, programs generated
by mindless selection”*
*Maynard Smith. J (2000) The concept of information in biology. Phil. of Sci., 67:177-194

25. Microbes as Signs and Signals
Every biological entity is a sign and a signal
……………..
“Yet they are equally part of the superorganism
genome with which we engage the rest of the
biosphere”
Joshua Lederberg, “Infectious History” (2000)

26. Reception
Transmitter
Emission
Receiver
Transmission
Process
Transmission
Transmission: Components, Stages, Causes
Why transmission How transmission
How transmission reaches
receiver

27. Patch
Emigration
Patch
Migration Inmigration
Colonization
Transmission
(transfer)
Social pressure
Genetic polymorphism
Boarder (host) characteristics
Movement cues
Mortality
Conspecific attraction
Interspecific facilitation
Social fence
Modified from Ims RA and Yoccoz, NG, in “Metapopulation Biology”, Hanski and Gilpin
Transmission components, stages, and some causal mechanisms
Dispersal

28. Inmigration
Colonization
Patch
Emigration
Patch
Migration
Theoretical transmittology
(metadosiology)
“Theoretical epidemiology” has been
used to cover mathematical modeling to
study the dynamics of infectious diseases.
NOT to examine the possible
causes of transmission events

29. Why Be a Vagabond When You Can Stay at Home?*
The question: Levin, B. R., & Bergstrom, C. T. (2000). Bacteria are different: observations,
interpretations, speculations, and opinions about the mechanisms of adaptive evolution in prokaryotes.
PNAS, 97: 6981
• Because there is no enough room at home
• Because there is too many people at home
• Because there is no possibilities for my progeny at home
• Because there is no enough food at home
• Because there are conflicts at home
• Because home is a dangerous, unstable environment
• Because I feel attacked at home
• Because I am expelled from home
• Because I am looking for my own place in the world
• Because I am looking for a different style of life
• Because I have more mating possibilities outside
• Because I am an explorer Bacteria are NOT
different !!

30. Why Be a Vagabond When You Can Stay at Home?*
The question: Levin, B. R., & Bergstrom, C. T. (2000). Bacteria are different: observations,
interpretations, speculations, and opinions about the mechanisms of adaptive evolution in prokaryotes.
PNAS, 97: 6981
• Because there is no enough room at home
• Because there is too many people at home
• Because there is no possibilities for my progeny at home
• Because there is no enough food at home
• Because there are conflicts at home
• Because home is a dangerous, unstable environment
• Because I feel attacked at home
• Because I am expelled from home
• Because I am looking for my own place in the world
• Because I am looking for a different style of life
• Because I have more mating possibilities outside
• Because I am an explorer
Bacteria are NOT different !!
Habitat saturation and transmission
Intermicrobial competition and transmission
Host defenses, antibiotics?, hygiene
Speciation-clonalization, recombination
Replication as transmission
Mechanisms for transfer and dispersal

31. Inmigration
Colonization
Patch
Emigration
Patch
Migration
Theoretical transmittology
(metadosiology)
“Theoretical epidemiology” has been
used to cover mathematical modeling to
study the dynamics of infectious diseases.
NOT to examine the possible
causes of transmission events

32. Why Be at Home When You Can be Free Outside?
The question: Levin, B. R., & Bergstrom, C. T. (2000). Bacteria are different: observations,
interpretations, speculations, and opinions about the mechanisms of adaptive evolution in prokaryotes.
PNAS, 97: 6981
• Because there is a very stable environment
• Because there I am out of external dangerous influences
• Because there I am protected
• Because there is a full system assuring my maintenance
• Because there are only predictable changes
• Because I am in equilibrium with local entities
• Because many of my needs are provided without wor
• Because I found my own place in the world
• Because my replication is assured
• Because I am an exploiter
Bacteria are NOT
different !!

33. Inmigration
Colonization
Patch
Emigration
Patch
Migration
Theoretical transmittology
(metadosiology)
Vehicles
Ecology of Transmission

34. Vehicles for Transmission
Vehicle is any discrete (individual) biological entity which
houses replicator biological entities… and which can be
regarded as a machine that preserve and propagate the
replicators that ride inside it.
(Slightly improved from the original definition from R. Dawkins, 1982)
The Dawkins’ definition implies the notion of “interactor”, so that
vehicles and replicators are a “cohesive whole”
(D.L. Hull, 1980, 1981)

35. Gene
Gene
capture
platform
Mobile
genetic
element
Bacterial
clone
Host
(patient, carrier) Environment
Baquero et al., Public Health Evolutionary Biology of Antibiotic Resistance. Evolutionary Applications, 2015; Baez, del
Campo, Baquero et al. Microb Drug Resist. 2015 (about Franklin Gulls)
Vehicles inside Vehicles
A multilevel cascade of
transmissions and
introgressions
Biological entities are both
Occupants and Vehicles

36. Mutational
Path
Introgressive paths
Introgressive paths allows
transmission between different
fitness peaks
Crossing transmission bottlenecks

37. Gram -
Gram +
Gene
transmission via
plasmid vehicles
Plasmid vehicles
transmitting genes
between two different
microbial worlds
Lanza, V. F., Tedim, A., Martínez JL.,
Baquero, F., & Coque, T. M. (2015).
Microbiol Spectrum 3(1)

38. Gram -
Gram +
Gene
transmission via
plasmid vehicles
Plasmid vehicles
transmitting adaptive
genes (as Ab-R)
Lanza, V. F., Tedim, A., Martínez JL.,
Baquero, F., & Coque, T. M. (2015).
Microbiol Spectrum 3(1)
Svara, Rankin. BMC
Evolutionary Biology 11:130

39. JL Martínez, T Coque, F Baquero (2015) Nature Rev. Microbiol., 13:116-123
Introgression and Transmission Bottlenecks

40. JL Martínez, T Coque, F Baquero (2015)
Nature Rev. Microbiol., 13:116-123
Ranking the Risks of
Detection of Resistance
Genes in Resistomes
Mobile Genetic Elements as Vehicles
of Antibiotic Resistance Genes play a
Key-Role in the Risk Classification

41. Mutational
Path
Introgressive paths
Transmission Ecology
Crossing transmission bottlenecks

42. Crossing environments without vehicles
“Sit-and-wait transmission”
depending on the durable
stages in the environment
P. Ewald, 1987;
S. Bonhoeffer,
1996
…. Or sequences of patients
in a “contaminated” hospital
Transmission source

43. Transmission Waves and Türing Instability
Türing AM. (1952) The chemical bases of morphogenesis. Phil. Transact. Roy. Soc. London B
237:37 and Kauffmann SA (1993) The Origins of Order, Oxford University Press
Cuesta J, Manrubia S, Catalan P, and toyLIFE
team (2015, personal communication)
Interactive networks of
biological entities
change in different
environments
Transmission
Ecology

44. Leventhal, Hill, Nowak, Bonhoeffer. Evolution and emergence of infectious diseases in theoretical and real-
world networks. Nature Comm. 6:6101, 2015, Salathé
Green: susceptible or cured
Spread
Endemics,
equilibrium
source
Might an improved mutant
for transmission displace
the source strain?
mutant
Star graph: hubs
facilitate spread
(superspreaders)
Emergence of
strain variants
Infected hubs by the
source strain prevents
variant spread
Small world.
Local
transmission
Consider
protecting
individuals based
on their position
in the contact
network

45. January 2014
A
B

46. Leventhal, Hill, Nowak, Bonhoeffer. Evolution and emergence of infectious diseases in
theoretical and real-world networks. Nature Comm. 6:6101, 2015 6:6101, 2015
Transmission Networks in Different
Environments
Transmission
Ecology

47. Marcel Salathé et al. 2010; PNAS 107:22020-22025
Strength interactionsNumber of interactionsDegree
Close Proximity Interactions Relevant for Transmission of Respiratory Diseases in
an American High School, detected by wireless sensor network technology

48. Transmissible diseases?
• Diseases are never transmissible, as they result from an
interaction: the microbial agent doing something (in-fection,
from Latin “inficere” (in+facere) inside the host.
• What is transmissible is only the microbial agent
• The type of disease might contribute to the transmission of
the agent (cough, diarrhea…), and the transmission of hosts,
eventually carrying secondary hosts, influences the
transmission of the microbial agent.
• The host is a vehicle for the microbe’s transmission

49. Emergence
Transmissio
n
Introgression
Evolution
Transmission as a Central Process in Biology

50. Particular “intellectual” thanks to:
• Teresa M. Coque
• Val Fernández Lanza
• José-Luis Martínez (CNB-CSIC)
• Rosa del Campo
• Ana Sofía P. Tedim
• Victor de Lorenzo (CNB-CSIC)
• Juan-Carlos Galán
• Carlos Llorens (Biotechvana)
• Bruce Levin (Emory University)
• Eric Bapteste (Pierre and Marie Curie University, Paris)
• Rob Willems (Utrech University)
• Andrés Moya and Amparo Latorre (Valencia University)
• Rafael Cantón and the Dpt. of Microbiology, Ramón y Cajal Hospital, Madrid

51. Ecology of the transmission process
Nature, 280:361, 1979

52. Cover page of Nature Reviews Microbiology in relation with paper “Pieces and patterns in
Genetical Engineering of Bacterial Pathogens” 2:510 (F. Baquero, 2004)

53. Türing Instability and Transmission Waves
Türing AM (1952). Philos. Trans. Roy. Soc. London B, 237:37, and Kauffman SA (1993) The Origins
Equilibrium between x and y.
x population is locally increasing
Increase in x is followed by an
increase in y, but increase in y
competes with x